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Photogeochemistry of minerals under anoxic conditions
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Liu, Winnie. Photogeochemistry of minerals under anoxic conditions. Retrieved from https://doi.org/doi:10.7282/t3-jxb1-ke93

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TitlePhotogeochemistry of minerals under anoxic conditions
NameLiu, Winnie (author); Falkowski, Paul (chair); Yee, Nathan (member); Piotrowiak, Piotr (member); Bermingham, Katherine (member); Rutgers University; School of Graduate Studies
Date Created2021
Other Date2021-10 (degree)
SubjectBiogeochemistry, Geochemistry, Photochemistry
Extent1 online resource (ix, 137 pages) : illustrations
DescriptionPhotogeochemistry, photochemical reactions with natural minerals and aqueous species, has influenced the biogeochemistry of Earth. Excitation of electrons in semi-conducting materials such as minerals can initiate thermodynamically unfavorable reactions. In particular, reactions caused by high energy UV radiation during early Earth could have influenced the surface environment of Earth by changing the availability of chemical species. This period of time is characterized by the lack of oxygen and enhanced UV radiation due to the absence of ozone. Photochemical reactions in anoxic environments are performed using a 450 W Hg lamp and specially made quartz reaction cells. The photochemistry of rhodochrosite (MnCO3), pyrite (FeS2), green rust ([Fe(II)1−x Fe(III)x(OH)2]x+.[(x/n)An−, mH2O]x−), amorphous Fe(II) silicate, and Fe(II) smectites were studied. UV irradiation of rhodochrosite and the Fe(II) silicates resulted in oxidation of the minerals. For rhodochrosite, a Mn(III) oxyhydroxide mineral manganite (γ-MnOOH) as well as H2 gas was produced. This demonstrates that mineral photochemistry is capable of producing manganese oxides abiotically from rhodochrosite under anoxic conditions. The irradiation of pyrite, particularly in the presence of dissolved Fe(II), resulted in the dissolution of pyrite and the release of sulfate and Fe(II). This process is a mechanism of weathering pyrite under anoxic conditions using light. The irradiation of green rust resulted in the production of magnetite (Fe3O4) and the irradiation of the two types of Fe(II) silicates resulted in the oxidation of Fe(II) without the formation of a secondary mineral phase. These reactions are previously unrecognized oxidation and/or transformation mechanisms under anoxic conditions that could have important implications for our understanding of the Archean S, Fe, and Mn cycles.
NotePh.D.
NoteIncludes bibliographical references
Genretheses
Persistent URLhttps://doi.org/doi:10.7282/t3-jxb1-ke93
LanguageEnglish
CollectionSchool of Graduate Studies Electronic Theses and Dissertations
Organization NameRutgers, The State University of New Jersey
RightsThe author owns the copyright to this work.
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